PARENT SESSION

(T362) INDUCTION OF MEIOTIC MATURATION IN MOUSE OOCYTES BY ADENOSINE ANALOGS.

Chen, Jing¹, Downs, Stephen¹, ¹ Department of Biological Sciences, Milwaukee, WI

ABSTRACT- In this study, we show that the adenosine analogs, 8-bromo-adenosine (8-Br-Ado) and methylmercaptopurine riboside (MMPR), but not adenosine, are very potent inducers of mouse oocyte maturation. Both 8-Br-Ado and MMPR stimulated oocyte maturation in oocytes maintained in prophase I arrest by a variety of meiotic inhibitors in dose-dependent fashion. Compound C, an inhibitor of AMP-activated protein kinase (AMPK), eliminated the effects of MMPR and 8-Br-Ado on oocyte maturation, which suggests that active AMPK may play a role in this process. Acetyl-CoA carboxylase (ACC) is an important substrate of AMPK, and western analysis of its phosphorylation state is commonly used as an indirect assay for AMPK activity. Western analysis using anti-phospho-ACC showed that GV-stage oocytes after 2h treatment with MMPR and 8-Br-Ado have increased levels of phospho-ACC compared to the untreated control. The results indicate that AMPK is activated in 8-Br-Ado- or MMPR-treated oocytes before meiotic resumption. Oocytes treated with adenosine for 2h also contained high levels of phospho-ACC, but these levels decreased with longer culture (4-6h). This suggests that maintaining a high level of active AMPK is required for GVB. 8-Br-Ado and AICAR, an AMPK activator, significantly increased the percentage of oocytes maturing spontaneously to the metaphase II stage, but MMPR blocked this process. The inhibition of polar body formation by MMPR may be due to suppression of purine de novo synthesis. However, other purine de novo synthesis inhibitors, azaserine and aminopterin, had no effect on polar body formation. Taken together, these data support the idea that adenosine analogs promote meiotic maturation in mouse oocytes through activation of AMPK. Supported by funds from the NIH (HD040392).

KEY WORDS: adenosine analog, meiotic resumption, AMPK, mouse oocyte